Herbicide spraying proposed to curb broom plants in small parts of Mendocino National Forest

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See a map of the Mendocino National Forest showing sites to be sprayed for the eradication of invasive broom plants within the Ranch fire footprint here.

Mendocino National Forest plans to use herbicides and hand tools to remove and control invasive broom plants now sprouting in the footprint of the Ranch fire, which in 2018 scorched about 288,000 acres in the sprawling forest that spans Lake, Glenn and Colusa counties.

The U.S. Forest Service, which manages the rugged woodlands, says the broom treatment project needs to start in spring to prevent regrowth of Scotch, Spanish and French broom plants, which can form impenetrable thickets and constitute a wildfire hazard, said Punky Moore, a Mendocino National Forest spokeswoman.

While the fire destroyed many of those mature broom plants, it also stimulated the germination of seeds in the ground that might otherwise have remained dormant for years or decades. Now those young plants are nearly a year old, she said. By the summer of 2021, they will have matured and begun to drop new seeds.

“Herbicide treatment must occur quickly to be effective,” the national forest said in a letter announcing the project and a legally mandated environmental analysis.

The Ranch fire, the largest in state history, scorched more than 410,000 acres in all. Salvage logging also is occurring in burned areas of the 913,000-acre national forest.

The proposed ground-level spraying of seedlings and uprooting of larger adult plants would occur at 15 sites scattered around the fire area, comprising a total of 54 acres. Most of the broom-infested sites are near roads, but not in places where people would come in contact with the plants to be treated with backpack sprayers, said Lauren Johnson, an ecosystem staff officer with the national forest.

Once the herbicide solution dries on the plants, it will not rub off on skin or clothing or wash off the plant, she said.

Herbicides may harm or kill any vegetation they contact and some herbicides are harmful to fish and amphibians, but the Forest Service does not spray near water and applies just enough solution to wet the leaves of target plants and not allow any to drip onto the soil, Johnson said.

The largest broom infestation is on Sumner Ridge, with others near Letts Lake, which remains closed, and along the M1 road. There are also broom plants targeted for spraying at the north end of Lake Pillsbury. No herbicide spraying will be done within the Snow Mountain Wilderness and no aerial spraying is proposed.

The Forest Service will notify the public before any spraying begins and will post information at the specific locations, Johnson said.

The three broom species in the forest have bright yellow flowers, small leaves and pea-pod type fruits. They were widely planted as ornamentals and for erosion control starting in the late 1880s, but Scotch broom in particular was recognized as a problem in California in the 1930s.

The plants are not palatable to wildlife and their ability to fix nitrogen improves soil fertility, giving a competitive edge to other nonnative plants.

The proposed herbicide would be a mixture of triclopyr and aminopyralid, along with a seed oil surfactant and a marker dye.

Tom Wheeler, executive director of the Arcata-based Environmental Protection Information Center, said the herbicides were “relatively benign” and the impact would largely depend on the application process.

“I don’t think there’s a good reason to be concerned,” he said, acknowledging that many people are opposed to herbicide use.

Moore said the Forest Service “recognizes public participation as a valuable part” of the project planning process. Public comments may be submitted by Jan. 21 and sent by email message or attachment to:

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@press On Twitter @guykovner.

See a map of the Mendocino National Forest showing sites to be sprayed for the eradication of invasive broom plants within the Ranch fire footprint here.

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